1. Field of the Invention
The present invention relates to a board inspection apparatus and method applied for inspecting a breakage in a part of pattern on a board in which a narrow-pitch conductor pattern is printed (hereinafter, referred as to xe2x80x9cboardxe2x80x9d where a LSI package which is in the run-up to implementing an IC chip is included in the xe2x80x9cboardxe2x80x9d).
2. Prior Art
Heretofore, an apparatus and method for detecting a conduction condition of a narrow-pitch conductor pattern printed on a board have widely been known in which a signal is applied to one edge of a pattern line of the conductor pattern, the applied signal is received at another edge of the pattern line, and the conduction condition is inspected in accordance with an amplitude of the received signal.
Such an inspection apparatus was also disclosed by the present applicant in Japanese Patent Application No. HEI08-104148 titled xe2x80x9can inspection apparatus using a non-contact shielded probexe2x80x9d.
In these prior arts including Japanese Patent Application No. HEI08-104148, a pulse signal which includes an alternate current component having a predetermined frequency is used as an inspection signal. A conduction condition is judged in accordance with a size of difference between the average value calculated from a received level of the inspection signal and a threshold value.
However, in these conventional inspection method and apparatus, bags of time has been required to complete the inspection on all patterns of the board as an inspecting object due to the necessity of calculation for determining the average value, which requires a time for receiving a plural period of signal. Particularly, since a number of pattern line and terminal in existing boards is large, for example 1000 of sample number, it is necessary to spend 5 seconds for completing an inspection of one board even when it, for example, spends 5 ms to inspect one pattern line and terminal. Therefore, the improved efficiency in this field is desired.
The present invention suggests an inspection apparatus and method capable of a effective conduction inspection of a pattern line on a board. To achieve the object, according to one aspect of the present invention, there is provided a board inspection apparatus including a predetermined transmitter applying a signal to one edge of a pattern line on a board, a predetermined probe receiving a signal from another edge of the pattern line, wherein a conduction of the pattern line is inspected in accordance with the received signal, the improvement comprises an applying device for applying an inspection signal to the one edge of the pattern line at a predetermined time; an informing device for informing an applied timing of the inspection signal to a signal pick-up device, wherein the signal pick-up device includes a monitoring device for monitoring a variance of a received signal which is detected by the probe.
Since the monitoring of the signal variance may be executed after receiving the information, an effective processing in the monitoring device can be achieved. In particular, an arrival of the received signal corresponding to the inspection signal may be expected, which allows the inspection signal to be adapted to a few number of pulse signals, such as one to two, resulting in an effective processing as a whole.
The aforementioned object is applicable to an apparatus for inspecting a plurality of pattern lines. Thus, according to another aspect of the present invention, there is provided a board inspection apparatus including a predetermined transmitter applying a signal to each one edge of pattern lines on a plurality of boards, predetermined probes receiving signals from each another edge of the pattern lines, wherein each conduction of the pattern lines is inspected in accordance with the received signals, the improvement comprises a source for generating an inspection signal; a plurality of applying devices for approximately simultaneously applying an inspection signal to each the one edge of pattern lines on a plurality of boards at a predetermined time; a plurality of informing devices for informing an applied timing of the inspection signal; and a plurality of monitoring devices for monitoring a variance of each received signal which is detected by each of the probes.
In the second aspect of the present invention, each the applying device, each the informing device and the plurality of monitoring devices may be configured as one channel. Easier entire control may be achieved by making up such a channel. In addition, it becomes possible to configure the entire inspection apparatus as a modular configuration.
According to another preferable embodiment of the present invention, the predetermined transmitter may be a signal applying terminal contacting the one edge, and the probe may is a non-contact shielded probe. Further, according to other preferable embodiment of the present invention, the predetermined transmitter may be a non-contact type of signal applying terminal, and the probe may be a signal applying terminal contacting to the another edge.
That is, in the present invention, a non-contact type of probe may be applied both to the transmitting side and the receiving side, which contributes the size reduction. According to still other preferable embodiment of the present invention, the inspection signal may be a pulse having a length equal to at least one period, which contributes the speeding up of the inspection operation.
According to yet other preferable embodiment of the present invention, the inspection signal may have a sine waveform. Since no higher harmonic component is included in the sine waveform, noise resistance characteristics is enhanced in the entire inspection apparatus.
According to other preferable embodiment of the present invention, the inspection signal may have a rectangular waveform. Since a peak detection in the rectangular waveform can be rapidly and surely carried out, more effective inspection operation may be expected.
According to other preferable embodiment of the present invention, the monitoring device may detect a first peak of a waveform of the received signal after the informing. In addition, the first peak may be a primary peak after the informing, which contributes to shorten the inspection time. In this case, the board inspection apparatus may further include a detection device for detecting variant amount of the received signal from the time when the first peak is detected to the time when a subsequent second peak is detected.
According to other preferable embodiment of the present invention, the applying device may further include a signal source for generating a pulse signal, and initiate to energize the signal source at the applied timing. The inspection signal can be created within a short time by turning on/off the signal source.
According to other preferable embodiment of the present invention, the applying device may further include a signal source for continuously generating a pulse signal, and a switch connected to the signal source and to the terminal of the pattern line of the board, wherein the switch is turned off at the applied timing. Allowing to continuously energize the signal source can improve the accuracy of a waveform of the inspection signal.
To achieve the object described above, according to other aspect of the present invention, there is provided a board inspection method including steps of: applying a signal to one edge of a pattern line on a board; receiving a signal at another edge of the pattern line by a predetermined probe; inspecting a conduction of the pattern line in accordance with the received signal, the improvement comprises applying an inspection signal to the one edge of the pattern line at a predetermined time; informing an applied timing of the inspection signal to a receiving device; and monitoring a variance of a received signal which is detected by the probe after receiving the informing signal.
In particular, it is desirable to use a pipeline operation for the high speed inspection. Hereat, according to other preferable embodiment of the present invention, the board inspection method further include; a converting step for converting the received signal by A/D conversion; and a collecting step for collecting a data from the A/D conversion, wherein the converting step and the collecting step may be configured to perform a pipeline operation.